Experimental Investigation and Numerical Simulation of Liquid Droplet Vaporization in a Compression System With Wet Compression

2004 ◽  
Author(s):  
Kunpeng Zhang ◽  
Song Zou ◽  
Weiming Pan ◽  
Fei Xue
Keyword(s):  
Cooling System ◽  
Liquid Droplet ◽  
Spray Cooling ◽  
Liquid Droplets ◽  
Compression Process ◽  
Compression System ◽  
Droplet Vaporization ◽  
Spray System ◽  
Good Accord ◽  
Wet Compression

Experimental study of spray cooling system with wet compression has been carried out on a small hot wind tunnel. A mathematical model is established for liquid droplets evaporization and a 3D calculation bound on the model have been carried out. The results are in good accord with the experimental data. This paper will be good reference for spray system design for a wet compression system. And the detail information of the experiment and numerical computation take us further understanding of the real wet compression process.

Theory Analysis and Experimental Investigation of Liquid Droplets Evaporization in High Speed Flow

Volume 3 ◽  
2004 ◽  
Author(s):  
Kunpeng Zhang ◽  
Song Zou ◽  
Haigui Wang ◽  
Weiming Pan ◽  
Fei Xue
Keyword(s):  
Mathematical Model ◽  
High Speed ◽  
Cooling System ◽  
Liquid Droplets ◽  
Theory Analysis ◽  
Compression Process ◽  
Spray System ◽  
Speed Flow ◽  
Wet Compression ◽  
The Mathematical Model

Experimental study of spray cooling system with wet compression has been carried out on a small hot wind tunnel. A mathematical model is established for liquid droplets evaporization and a set of experiments have been carried out to study the inherent law of liquid spray with evaporization. The experiment result is accord with the theory analysis. The result of this paper will be good reference for spray system design for a wet compression system. And the detail information of the experiment and the mathematical model take us further understanding of the real wet compression process.

scholarly journals Experimental investigations of spray flow rate and angle in enhancing the performance of PV panels by steady and pulsating water spray system

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Mojtaba Nateqi ◽  
Mehran Rajabi Zargarabadi ◽  
Roohollah Rafee
Keyword(s):  
Cooling System ◽  
Spray Cooling ◽  
Spray Angle ◽  
Experimental Investigations ◽  
Water Spray ◽  
Maximum Increase ◽  
Photovoltaic Panel ◽  
Electrical Efficiency ◽  
Spray System ◽  
Pv Panel

AbstractIn this study, a spray cooling system is experimentally investigated to increase the photovoltaic panel efficiency. Cooling of photovoltaic panels is one of the important parameters that affects the PV panel performance. In this experiment the effects of spray angle, nozzles to PV panel distance, number of nozzles, and pulsating water spray on the PV panel performance are investigated. For this purpose, an experimental setup was made. The spray angles varied from 15° to 50°. The comparison between the spray angles shows that by decreasing the spray angle to 15° increases the electrical efficiency of PV panel to 19.78% and simultaneously the average PV panel temperature decreases from 64 (for non-cooled PV) to 24 °C. Also, nozzle to PV panel distance was changed from 10 to 50 cm. The best result was obtained for the lowest distance by 25.86% increase in power output. Study of various frequency also show that due to the surface evaporation and the intensity of the radiation, increasing the water spraying frequency can increase or decrease the electrical efficiency. The On–Off water spray system results show that the maximum increase in efficiency was obtained with frequency of 0.2 Hz which it was 16.84%. Water consumption also decreased to half.

Determining Parametric Effects for Droplet Evaporation on Nanoporous Superhydrophillic Surfaces Using Machine Learning Techniques

2021 ◽  
Author(s):  
Emma R. McClure ◽  
Van P. Carey
Keyword(s):  
Machine Learning ◽  
Cooling System ◽  
Spray Cooling ◽  
Droplet Evaporation ◽  
Contact Angles ◽  
Machine Learning Techniques ◽  
Metallic Surfaces ◽  
Droplet Spreading ◽  
Droplet Vaporization ◽  
Speed Accuracy

Abstract Experimental results demonstrate that droplet vaporization on metal surfaces can be significantly enhanced with the application of a nanoporous, superhydrophilic surface coating. A thin layer of ZnO nanopillars can be easily seeded and grown on most metallic surfaces to achieve nanoscale pores between pillars, and ultra-low apparent contact angles. These surface coatings have the potential to improve spray cooling processes, and can be easily scaled up to larger and more complex heat exchangers. In order to characterize the potential improvement to a spray cooling system it is important to understand the dependence on system parameters, and to have a clear model of droplet vaporization on such surfaces. There are a number of surface and impact parameters that will affect the droplet spreading and subsequent vaporization on the surface. The surface contact angle, wicking speed and impact velocity all interact to affect the maximum spread of the droplet and the speed at which the droplet reaches this state. Along with variations in droplet volume and wall superheat, the model for droplet vaporization becomes more complex and nonlinear. Instead of exploring a single parameter at a time, machine learning tools can be utilized to determine the dependence of droplet evaporation time on these parameters simultaneously. In this study a genetic algorithm and a neural network were used to develop a droplet evaporation model for these superhydrophilic surfaces. Each algorithm demonstrated clear advantages depending on whether speed, accuracy, or an explicit mathematical model was prioritized.

Spray Cooling for Time Resolved Emission Measurements of ICs

2004 ◽  
Author(s):  
Rama R. Goruganthu ◽  
David Bethke ◽  
Shawn McBride ◽  
Tom Crawford ◽  
Jonathan Frank ◽  
...  
Keyword(s):  
Heat Flux ◽  
Thermal Performance ◽  
Flip Chip ◽  
Cooling System ◽  
Spray Cooling ◽  
Junction Temperature ◽  
Maximum Temperature ◽  
Uniform Heat Flux ◽  
High Heat Flux ◽  
Time Resolved

Abstract Spray cooling is implemented on an engineering tool for Time Resolved Emission measurements using a silicon solid immersion lens to achieve high spatial resolution and for probing high heat flux devices. Thermal performance is characterized using a thermal test vehicle consisting of a 4x3 array of cells each with a heater element and a thermal diode to monitor the temperature within the cell. The flip-chip packaged TTV is operated to achieve uniform heat flux across the die. The temperature distribution across the die is measured on the 4x3 grid of the die for various heat loads up to 180 W with corresponding heat flux of 204 W/cm2. Using water as coolant the maximum temperature differential across the die was about 30 °C while keeping the maximum junction temperature below 95 °C and at a heat flux of 200 W/cm2. Details of the thermal performance of spray cooling system as a function of flow rate, coolant

Numerical Analysis of Influence of Roughness of Material Surface on High-Speed Liquid Droplet Impingement

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Hirotoshi Sasaki ◽  
Yuka Iga
Keyword(s):  
Numerical Analysis ◽  
High Speed ◽  
Erosion Rate ◽  
Liquid Droplet ◽  
Material Surface ◽  
Liquid Droplets ◽  
Fluid Machinery ◽  
Droplet Impingement ◽  
Surface Liquid ◽  
Droplet Impingement Erosion

This study explains why the deep erosion pits are formed in liquid droplet impingement erosion even though the droplets uniformly impinge on the entire material surface. Liquid droplet impingement erosion occurs in fluid machinery on which droplets impinge at high speed. In the process of erosion, the material surface becomes completely roughened by erosion pits. In addition, most material surface is not completely smooth and has some degree of initial roughness from manufacturing and processing and so on. In this study, to consider the influence of the roughness on the material surface under droplet impingement, a numerical analysis of droplets impinging on the material surface with a single wedge and a single bump was conducted with changing offsets between the droplet impingement centers and the roughness centers on each a wedge bottom and a bump top. As results, two mechanisms are predicted from the present numerical results: the erosion rate accelerates and transitions from the incubation stage to the acceleration stage once roughness occurs on the material surface; the other is that deep erosion pits are formed even in the case of liquid droplets impinging uniformly on the entire material surface.

scholarly journals Study on the effect of Weber Number to heat transfer of multiple droplets on hot stainless steel surface

2018 ◽  
Vol 154 ◽  
pp. 01114 ◽  
Author(s):  
Aria Riswanda ◽  
Indro Pranoto ◽  
Deendarlianto ◽  
Indarto ◽  
Teguh Wibowo
Keyword(s):  
Stainless Steel ◽  
Surface Temperature ◽  
Weber Number ◽  
Steel Surface ◽  
Cooling System ◽  
Spray Cooling ◽  
Stainless Steel Surface ◽  
Temperature Decrease ◽  
Evaporation Time ◽  
Decrease Rate

Multiple droplets are drops of water that continuously dropped onto a surface. Spray cooling is an application of the use of droplet on a cooling system. Spray cooling is usually used in a cooling system of electronic devices, and material quenching. In this study, correlations between Weber number and surface temperature decrease rate during multiple droplets impingement are investigated and analyzed. Visualization process is used to help determine the evaporation time of droplets impingement by using high speed camera. Induction stove is used to maintain a stainless steel surface temperature at 120°C, 140°C, and 160°C. The Weber number was varied at 15, and 52.5 to simulate low and medium Weber number. The result of this study shows that increase in Weber number does not increase the temperature decrease rate noticeably. Whereas the Weber number decrease the time required for surface temperature to reach its lowest surface temperature. It was also found that for low and medium Weber number, Weber number affect the evaporation time of multiple droplets after impingement.

An Entropy Based Evaluation of Efficiency of a Transonic Compressor Rotor With Water Injection

2008 ◽  
Author(s):  
Istvan Szabo ◽  
Mark G. Turner
Keyword(s):  
Viscous Dissipation ◽  
Entropy Generation ◽  
Dissipation Function ◽  
Entropy Generation Rate ◽  
Thermodynamic Efficiency ◽  
Compression Process ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
Wet Compression ◽  
Isentropic Efficiency

Defining the thermodynamic efficiency of the wet compression process in a compressor is not trivial, since the flow in this case has multiple phases present which interact with each other. In this paper, an approach is presented that calculates the overall entropy creation and thus the isentropic efficiency of a wet compression process in a transonic compressor rotor. The viscous dissipation function is calculated everywhere in the domain in the post-processing phase of the CFD simulation and integrated to the wall, with special treatment in the near-wall regions where high rates of entropy generation occur. The isentropic efficiency of the wet compression is then determined from the entropy generation rate. Analytical integration of wall functions and numerical integration of the viscous dissipation function allows for reasonable results even with relatively coarse grids and can be applied for single-phase flows. The methodology presented is also useful to quantify the efficiency of thermodynamic processes in devices that introduce streams into the flow path, such as cooled turbines and compressors with flow control.

Influence of Water Droplet Size and Temperature on Wet Compression

2007 ◽  
Author(s):  
M. Bianchi ◽  
F. Melino ◽  
A. Peretto ◽  
P. R. Spina ◽  
S. Ingistov
Keyword(s):  
Gas Turbine ◽  
Water Droplet ◽  
Droplet Diameter ◽  
Axial Compressor ◽  
Combined Cycle ◽  
Water Evaporation ◽  
Air Cooling ◽  
Compression Process ◽  
Two Phase ◽  
Wet Compression

In the last years, among all different gas turbine inlet air cooling techniques, an increasing attention to fogging approach is dedicated. The various fogging strategies seem to be a good solution to improve gas turbine or combined cycle produced power with low initial investment cost and less installation downtime. In particular, overspray fogging and interstage injection involve two-phase flow consideration and water evaporation during compression process (also known as wet compression). According to the Author’s knowledge, the field of wet compression is not completely studied and understood. In the present paper, all the principal aspects of wet compression and in particular the influence of injected water droplet diameter and surface temperature, and their effect on gas turbine performance and on the behavior of the axial compressor (change in axial compressor performance map due to the water injection, redistribution of stage load, etc.) are analyzed by using a calculation code, named IN.FO.G.T.E. (INterstage FOgging Gas Turbine Evaluation), developed and validated by the Authors.

Simulation of Impaction Between Liquid Droplet and Solid Particles Based on SPH Method

2014 ◽  
Author(s):  
Shuai Meng ◽  
Qian Wang ◽  
Rui Yang
Keyword(s):  
Surface Tension ◽  
Solid Particle ◽  
Liquid Droplet ◽  
Particle Interaction ◽  
Solid Particles ◽  
Seed Particle ◽  
Liquid Droplets ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Spray Granulation

The phenomenon of impaction between liquid droplets and solid particles is involved in many scientific problems and engineering applications, such as impaction between sprayed droplet and solid particles in limestone injection desulfurization system and the collision between a droplet of the liquid to be granulated and a seed particle in fluidized bed spray granulation process. There are a lot of factors affected this phenomenon: droplet and particle size, momentum of both liquid droplet and solid particles, materials, surface conditions of the solid particles and so on. However the experimental or numerical researches have been done mostly pay attention to Specific application or process, so the impaction phenomenon has not been through studied, for example how different factors affected the impaction process with its effect on different applications. This paper focuses on the basic issue of interaction between droplet and solid particles. Three main factors were considered: ratio of diameter between the droplet and solid particle, relative velocity and the surface tension (including the contact angle between droplet and solid particle). All the study is based on simulation using SPH (smoothed particle hydrodynamics) method, and the surface tension is simulated by particle-particle interaction.

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